1. Field of the Invention
The present invention relates to a television receiver, and more particularly, to a receiver for receiving both HDTV and NTSC signals, and a method for selectively receiving either HDTV or NTSC signal.
2. Description of Related Art
The "Grand Alliance" Advanced Television system (GA-ATV) is a digital television transmission system standard which can replace NTSC. The GA-ATV system (also called GA-HDTV or GA-VSB) is standardized by an advanced television system committee (ATSC) and adopts a vestigial side band (VSB) modulation method of digital transmission.
A new ATV signal is transmitted simultaneously with a conventional analog television broadcasting signal (NTSC) via a TV channel which is presently not used in a given geographic region (called a "taboo" channel). Thus, the GA-VSB receiver must be designed to resist interference from the NTSC signal.
The GA-VSB receiver corresponding to a USA-type terrestrial broadcasting HDTV standard is disclosed in the following reference: [1] ATSC Digital Television Standard, September., 1995. FIG. 1 shows the configuration of the above-described GA-VSB receiver.
Referring to FIG. 1, the receiver is comprised generally of a tuner 102, a demodulator 104, an NTSC interference canceler 106, a signal processor 108, and a display 110. The tuner 102 receives an HDTV signal transmitted from a transmitter. The demodulator 104 demodulates the output of the tuner 102. The NTSC interference canceler 106 cancels a modulation carrier of an NTSC signal existing in the output of the demodulator 104. The signal processor 108 equalizes the output of the NTSC interference canceler 106, corrects errors in the equalized signal and restores the error-corrected signal to an image signal. The display 110 displays the output of the signal processor 108.
In the event HDTV broadcasting starts, a couple of problems must be dealt with. First, coexistence with NTSC broadcasting cannot be avoided, and a receiver must be structured to allow viewers to watch either HDTV or NTSC broadcasting at will. Second, a channel may be an NTSC broadcasting channel or a HDTV broadcasting channel depending on geographic location. Thus, since in practice a channel may have both the NTSC and HDTV signals, a structure whereby either of the two broadcastings can be watched is required. However, the conventional GA-VSB receiver shown in FIG. 1 has a structure allowing viewers to watch only HDTV broadcasting.